I recently did my own headliner in my 66 and it came out pretty good but now the material is coming loose from my sail panels. What can I use that will dry and keep the material on.

3m spray adhesive.

Is it the material on the sail panel itself or the material that is behind the sail panel and part of the head liner?

Most spray on contact adhesives will work but 3M makes the best. With any porous surface, you must apply two coats to each surface. Spray the first and then let it dry. This will seal the surface. The second coat should be allowed to dry until your clean finger does not remove adhesive when touched but the adhesive is still tacky. Lay on the fabric. You get 1 shot so a couple sets of hands may be required. Start from one end and work to the other smoothing as you go.